Power supply circuits



April 1966 R. K. WILLARDSON ETAL 3,246,225

POWER SUPPLY CIRCUITS Original Filed June 30, 1955 I87 l9l 5 5 g 203 201203 II 2 'a Y 3 5,1 202 |\8|a I820 2 O N 0 '84 [960 O I860 q; 206 204206 I830 I850 l g E O- WE I890 I900 a; E05

2|0 J Time v INVEN TOR.

Robert K. W|Hurds0n 7 y Albert C. Beer 824 22 .Fi g .Z s W ATTORNEYS.

United States Patent 3 Claims. (Cl. 321'-2) This is a division ofapplication Serial No. 806,184, filed April 13, 1959, now abandoned,which was a division of application Serial No. 519,070, filed June 30,1955, now US. Patent 2,889,492, patented June 2, 1959.

This invention relates to power supply circuits, and particularly tocircuits in which a direct voltage is converted into an alternatingvoltage.

In accordance with the present invention, a typical power supply circuitfor use with a direct voltage source comprises a first magnetoresistanceelement, a transformer, the first magnetoresistance element and a firstwinding of the transformer being connected to the direct voltage source,means for providing a varying magnetic field across the firstmagnetoresistance element, whereby an alternating voltage is providedacross a second winding of the transformer, a second magnetoresistanceelement connected to the second winding of the transformer, and meansfor providing across the second magnetoresistance element a varyingmagnetic field that has a maximum strength when the alternating voltageacross the second winding of the transformer is at a peak in onedirection and has a minimum strength when the alternating voltage is ata peak in the opposite direction.

In the drawings:

FIG. 1 is a schematic diagram of a power supply according to the presentinvention.

FIG. 2 is a schematic diagram of a rectifier circuit similar to therectifier portion of the circuit of FIG. 1.

FIG. 3 is a graph in rectangular coordinates of input voltage, magneticfield, resistance, and output voltage as functions of time in thecircuit of FIGS. 2 and 4.

FIG. 4 is a schematic diagram of a modification of the rectifier circuitof FIG. 2.

FIG. 2 illustrates the basic circuit of a magnetoresistance rectifier.One terminal of an A.-C. voltage source 180 is connected by a wire 181to an output terminal 182. The other terminal of the A.-C. voltagesource 180 is connected by a wire 183 to one end of a magnetoresistanceelement 184. The other end of the magnetoresistance element 184 isconnected by a wire 185 to the other output terminal 186. An A.-C.voltage source 187 is connected by wires 188, 189 across a coil 190. AD.-C. voltage source 191 is connected by wires 192, 193 across a coil194. The coils 190 and 194 have a core 195 of iron or other suitableferromagnetic material so constructed and positioned as to provide amagnetic field across the magnetoresistance element 184. A load 196 isconnected across the output terminals 182, 186. The A.-C. voltage source187 is operated in such manner as to provide a magnetic field that hasthe same frequency as, and is either in phase with or 180 out of phasewith, the A.-C. voltage supplied by the A.-C. voltage source 180.

FIG. 3 illustrates the operation of the circuit of FIG. 2.

The curve 200 represents the A.-C. input voltage pro- -vided by theA.-C. voltage source 180. The curve 201 represents the magnetic fieldacross the magnetoresistance element 184. The dashed line 202 indicatesthe magnetic field provided by the coil 194 connected to the D.-C.voltage source 191, while the curve 201 indicates the instantaneousmagnetic field provided by the coil 194 and by the coil 190 connected tothe A.-C. voltage source 187. Preferably tthe ferromagnetic core 195 ofthe coils 190, the 194 is driven to saturation during a large portion ofthe half cycle to provide maximum resistance in the magnctoresistanceelement 184 during a large portion of the half cycle. For such operationthe peaks of the magnetic field curve 201 are flattened, as is indicatedat 203-403. The curve 204 represents the resistance of themagnetoresistance element 184. The dashed line 205 indicates theresistance of the magnetoresistance element 184 obtained with themagnetic field provided by the coil 194 connected to the D.-C. voltagesource 191, as indicated by the dashed line 202, while the curve 204indicates the instantaneous resistance of the magnetoresistance element184 obtained with the magnetic field provided by the coil 194 and by thecoil 190 connected to the A.-C. voltage source 187, as indicated by thecurve 201. Because of the saturation of the ferromagnetic core 195during a large portion of the half cycle, the peaks of the resistancecurve 204 are flattened, as is indicated at 206-206. The curve 207represents the output voltage across the load 196 where the load 196 isa pure resistance. Where the load 196 is a complex load the outputvoltage curve 207 is the same but is shifted along the time axis becauseof the phase shift in the load 196. The ratio of maximum resistance 206to minimum resistance 208, the magnetoresistance ratio, is the ratio ofreverse to forward resistance of the magnetoresistance rectifier circuitof FIG. 2, and is the same as the ratio of the peak forward voltage 209to the peak reverse voltage 210.

Various modifications can be made in the circuit of FIG. 2. A singlecoil can be used in place of the two coils 190 and 194, the single coilbeing supplied with alternating current and direct current from sourceseither in series or in parallel.

FIG. 4 illustrates a modification of the circuit of FIG. 2. All of thecomponents indicated by the reference numerals a-196a in FIG. 4correspond respectively to the components having the same referencenumerals without the subscripts in FIG. 2. The circuit of FIG. 4 is thesame as the circuit of FIG. 2 except that in FIG. 4 the A.-C. voltagesource 187 is omitted and the coil a is connected by the wires 188a,189a across the same A.-C. voltage source 180a that provides the inputvoltage to the circuit, and except that the coil 194, the D.-C. voltagesource 191 and the connecting wires 192, 193 are omitted in the circuitof FIG. 4 and are replaced by a permanent magnet 197, which provides thesame magnetic field, as indicated by the dashed line 202 of FIG. 3.

The operation of the circuit of FIG. 4 is illustrated in FIG. 3, and isthe same as the operation of the circuit of FIG. 2. The phase relationsare such that when the A.-C.

input voltage 200 reaches a maximum, the magnetic field 201 and theresistance 204 of the magnetoresistance element 184 are at a minimum,and when the A.-C. input voltage 200 reaches its maximum in the reversedirection the magnetic field 201 and the resistance 204 are at theirmaximum values.

In the circuits of FIG. 2 and FIG. 4 the wave form of the rectifiedoutput 207 depends upon the amount of saturation of the ferromagneticcore 195 or 195a. The

portion of the half cycle during which the core 195 or half cycle.

used advantageously for rectifying small signals, as well as forrectifying high voltage, high current density inputs.

FIG. 1 illustrates a DC. power supply circuit in which a-directvoltageis converted into an alternating voltage that isstepped up andthen rectified. One terminal of a DC. voltage source 220 is connectedbya wire 221 to one end of the primary winding 222 of a step-uptransformer 223'. The other end of the primary winding 222 is connectedby a wire 224 to one end of a first magnetoresistance element 225. Theother end of the magnetoresistance element 225 is connected by a wire226 to the other terminal of'the DC. voltage source 220: An AC. voltagesource 227 is connected by wires 228, 229 across a coil 230 having acore 231. of iron or other suit able ferromagnetic material soconstructed and positioned as to provide a magnetic field across themagnetoresistance element 225. One end of the high-voltage sec ondarywinding 232: of the transformer 223 is connected by awire 233 to anoutput terminal 234. The other end of the secondary winding 232 isconnected by a wire 235 to one end of a second magnetoresistance element236. The other end of the magnetoresistance element 236 is connected bya wire 237 to the other output terminal 238. The AC. voltage source 227is connected by wires 239, 240 across a coil 241. The D'.C. voltagesource 220is connected by wires 242, 243 across a coil 244. The coils241 and 244 have a core 245 of iron or other suitable ferromagneticmaterial so constructed and positioned as to provide a magnetic fieldacross the magnetoresistance element 236. A load 246 is connected acrossthe output terminals 234, 238.

The DC. voltage source 220 provides a currentthrough the primary winding222 of the transformer 223 and through the magnetoresistance element225. The alternating current provided by the AC. voltage source 227through the coil 230 provides a continuously varying magnetic fieldacross the first magnetoresistance element 225 and thus continuouslyvaries the resistance of the element 225.. The continuous variation inthe resistance of the element 225 provides an opposite continuousvariation in the current through the magnetoresistance element 225'andthe primary winding 222 of the transformer 223. A high AC. voltage isthus provided across the secondary winding 232 of the transformer 223.The rectifier portion of the circuit of FIG. 1 operates in the samemanner as the circuit of FIG. 2, as is illustrated in FIG. 3. The curve200 in FIG. 3 represents the AC. voltage provided across the secondarywinding 232 of the transformer 223. The curve 201 represents themagnetic field across the magnetoresistance element 236. The dashed line202 indicates the magnetic field provided by'the coil 244 connected tothe DC. voltage source 220,

while the curve 201 indicates the instantaneous magnetic field providedby the coil 244 and by the coil 2 41 connected to the A.C. voltagesource 227. Since the AC. voltage source 227 connected across the coil241 is the same A.C. voltage source that is connected across the coil230 that varies the resistance of the magnetoresistance element 225, themagnetic field across the magnetoresistance element 236 is either inphase with or 180 degrees out of phase with the A.C. voltage across thesecondary winding 232 of the transformer 223. Preferably, theferromagnetic core 245 of the coils 241, 244 is driven to saturationduring a large portion of the half cycle to provide maximum resistancein the magnetoresistance element 236 during a large portion of the Forsuch operation the peaks of the magnetic field curve 201 are flattened,as is indicated at 203-203. The curve 204 represents the resistance ofthe magnetoresistance element 236. The dashed line 205 indicates theresistance of the magnetoresistance element 236 obtained with themagnetic field provided by the coil 244 connected to the DC. voltagesource 220, as indicated by the dashed line 202, while the curve 204indicates the instantaneous resistance of the magnetoresistance element236 obtained with the magnetic field provided by the coil 244 and by thecoil 241 connected to the AC. voltage source 227, as indicated by thecurve 201. Because of the saturation of the ferromagnetic core 245during a large portion. of the half cycle, the peaks of the resistancecurve 204 are flattened, as. is indicated at 206206. The curve 207represents the output voltage across the load 246 where the load 246 isa pure resistance. Where the load 246 is a complex load, the outputvoltage curve 207 is thesame but is shifted along the time axis becauseof the phase shift in the load. 246. The ratio of maximum resistance 206to minimum resistance 208, the magnetoresistance ratio, is the ratio ofreverse to forward resistance of the rectifier portion of the circuit ofFIG. 1, and is the same as the ratio of the peak forward voltage 209 tothe peak reverse voltage 210.

The load 246 in the circuit of FIG. 1', andthe loads 196 and 196a ofFIG. 2 and FIG. 4, respectively, may, of course, include conventionalfilters for the DC, output.

While the forms of the invention herein disclosed constitute preferredembodiments, it is not intended herein to describe all of the possibleequivalent forms or ramifications of the invention. It will beunderstood that the words used are words of description rather than oflimitation, and that various changes may be made Without departing fromthe spirit or scope of the invention herein disclosed.

What is claimed is:

1. A power supply circuit for use with a direct voltage sourcecomprising a first magnetoresistance element, a transformer, said firstmagnetoresistance element and a first winding of said transformer beingconnected to said direct voltage source, means for providing a varyingmagnetic field across said first magnetoresistance element, whereby analternating voltage is provided across a sec.- ond winding of saidtransformer, a second magnetoresistance element connected to said secondwindingof said transformerpand means for providing across said secondmagnetoresistance element a varying magnetic field that has a maximumstrength when said alternating voltage across said second winding ofsaid transformer is at a peak in one direction and has a minimumstrength when said alternating voltage is at a peak in the oppositedirection,

2. A power supply circuit for use with a direct voltage sourcecomprising a first magnetoresistance element, a transformer, saidfirst'magnetoresistance element and a first winding of said transformerbeing connected to said direct voltage source, a first electromagnetpositioned to provide a magnetic field across said firstmagnetoresistance element, means for supplying alternating current tosaid electromagnet, whereby an alternating voltage is provided across asecond winding of said transformer, a second magnetoresistance elementconnected to said second winding of said transformer, means forproviding a magnetic field across said second magnetoresistance element,and means for reducing said magnetic field during one half cycle of thealternating voltage across said second winding of said transformer andfor increasing said magnetic field during the other half cycle of saidalternating voltage.

3. A power supply circuit for use with a direct voltage sourcecomprising a first magnetoresistance element, a transformer, said firstmagnetoresistance element and a first winding of said transformer beingconnected to said direct voltage source, a first electromagnetpositioned to provide a magnetic field across said firstmagnetoresistance element, means for supplying alternating current tosaid electromagnet, whereby an alternating voltage is provided across asecond winding of said transformer, a second magnetoresistance elementconnected vto said second winding of said transformer, means includingan References Cited by the Examiner UNITED STATES PATENTS 543,843 8/1895Biggar 323-94 2,226,846 12/1940 Clark 338-32 Christensen 252-518 Hansen323-94 Mochel 252-518 Page 321-8 Millar 324-45 X Wu et al. 321-8 Pearson324-46 Hollrnann 338-32 Gordon 321-45 X Weiss 324-45 LLOYD MCCOLLUM,Primary Examiner. RALPH D. BLAKESLEE, Examiner.

Dedication 3,246,225.--R0bert 11:. Willardson, Arcadia, Calif. andAlbert 0. Beer, U0- lumbus, Ohio PQWER SUPPLY CIRdUITS. Patent datedApr. 12, 1966. Dedication filed May 7, 1973, by the assignee, TheBattelle Development Corporation. Hereby dedicates to the People of theUnited States the entire remaining term of said patent.

[Ojficial Gazette October 30, 1.973.]

1. A POWER SUPPLY CIRCUIT FOR USE WITH A DIRECT VOLTAGE SOURCECOMPRISING A FIRST MAGNETORESISTANCE ELEMENT, A TRANSFORMER, SAID FIRSTMAGNETORESISTANCE ELEMENT, A FIRST WINDING OF SAID TRANSFORMER BEINGCONNECTED TO SAID DIRECT VOLTAGE SOURCE, MEANS FOR PROVIDING A VARYINGMAGNETIC FIELD ACROSS SAID FIRST MAGNETORESISTANCE ELEMENT, WHEREBY ANALTERNATING VOLTAGE IS PROVIDED ACROSS A SECOND WINDING OF SAIDTRANSFORMER, A SECOND MAGNETORESISTANCE ELEMENT CONNECTED TO SAID SECONDWINDING OF SAID TRANSFORMER, AND MEANS FOR PROVIDING ACROSS SAID SECONDMAGNETORESISTANCE ELEMENT A VARYING MAGNETIC FIELD THAT HAS A MAXIMUMSTRENGTH WHEN SAID ALTERNATING VOLTAGE ACROSS SAID SECOND WINDING OFSAID TRANSFORMER IS AT A PEAK IN OEN DIRECTION AND HAS A MINIMUMSTRENGTH WHEN SAID ALTERNATING VOLTAGE IS AT A PEAK IN THE OPPOSITEDIRECTION.